This invention relates in general to valves and to semiconductor electromechanical devices, and in particular, to micromachined components formed from wafers of a semiconductor material, such as silicon, bonded together.
MEMS (micro electro mechanical systems) are a class of systems that are physically small, having features or clearances with sizes in the micrometer range or smaller (i.e., smaller than about 10 microns; as is well known, “micron” is another term for micrometer, a unit of length equal to 0.001 millimeter). These systems have both electrical and mechanical components. The term “micro machining” is commonly understood to mean the production of three-dimensional structures and moving parts of MEMS devices. MEMS originally used modified integrated circuit (e.g., computer chip) fabrication techniques (such as chemical etching) and materials (such as silicon semiconductor material) to micro machine these very small mechanical devices. Today there are many more micro machining techniques and materials available. The term “MEMS device” as may be used in this application means a device that includes a micro machined component having features or clearances with sizes in the micrometer range, or smaller (i.e., smaller than about 10 microns). It should be noted that if components other than the micro machined component are included in the MEMS device, these other components may be micro machined components or standard sized (i.e., larger) components. Similarly, the term “microvalve” as may be used in this application means a valve having features or clearances with sizes in the micrometer range, or smaller (i.e., smaller than about 10 microns) and thus by definition is at least partially formed by micro machining. The term “microvalve device” as may be used in this application means a device that includes a microvalve, and that may include other components. It should be noted that if components other than a microvalve are included in the microvalve device, these other components may be micro machined components or standard sized (i.e., larger) components.
Many MEMS devices may be made of multiple wafers (or plates) of material, which may be micromachined to form components of the MEMS device prior to assembly of the multiple wafers into a completed MEMS device. For example, such a MEMS device may be manufactured using suitable MEMS fabrication techniques, such as the fabrication techniques disclosed in U.S. Pat. No. 6,761,420, the disclosures of which are incorporated herein by reference; U.S. Pat. No. 7,367,359, the disclosures of which are incorporated herein by reference; Klassen, E. H. et al. (1995), “Silicon Fusion Bonding and Deep Reactive Ion Etching: A New Technology for Miscrostructures,” Proc. Transducers 95 Stockholm Sweden pp. 556-559, the disclosures of which are incorporated herein by reference; and Petersen, K. E. et al. (June 1991), “Surface Micromachined Structures Fabricated with Silicon Fusion Bonding,” Proc. Transducers 91 pp. 397-399, the disclosures of which are incorporated herein by reference.